1. Field of the Invention
The invention relates to starters for engines and generators, and is directed more particularly to starters of the type commonly used on lawn mowers, chain saws, snow blowers, marine outboard engines, and the like, wherein motors with 31/2-8 horse power typically are used.
2. Description of the Prior Art
It is known to provide starting devices for internal combustion engines, which devices are provided with a rope pulley which rotates as a coiled rope is pulled, and which is rotatably mounted on a stationary central shaft. The shaft is engaged by a retainer spring, or by a spring-biased retainer member, such that a frictional connection prevails between the retainer member and the shaft. The frictional connection causes pawls on the pulley to swivel radially outwardly from the central shaft axis when the pulley is rotated in the starting direction. Free ends of the pawls engage with inner teeth of a coupling which is connected with the crankshaft of the internal combustion engine and which is coaxial with the central shaft. The pawls drive the coupling to start the engine. Upon completion of the rope-pulling stroke, the starter recoils and the pawls retract.
Referring to FIGS. 1 and 2, it will be seen that a prior art starter of the type herein disclosed includes a circular metal housing 10 having an open side 12 and a substantially closed side 14. Centrally of the closed side 14 is an opening 16 in which is disposed a metal tubular center shaft 18. Rotatably mounted on the shaft 18 is a pulley 20 of a plastic material. The pulley 20 is provided with a peripheral trough 22 in which is wound a rope 24. The pulley 20 includes a hub portion 26 provided with a central recess 28 and two bores 30 outboard from, and on opposite sides of the central recess 28. In each of the bores 30 there is disposed a coil spring 32 and base portion 34 of a pawl 36. The pawl base portions 34 are adapted to rotate in the bores 30, such that the pawls 36 may pivot outwardly and inwardly of the pulley hub portion 26.
Referring to FIGS. 3-6, it will be seen that a brake assembly 40, having resistance to rotation, includes a retainer 42 having a central hub portion 44 complementary to the central recess 28 which is adapted to retain the hub portion 44. Extending from the retainer 42 are two protrusions 46 which are positioned so as to be engaged by the pawls 36. Disposed between a floor 48 of the pulley hub portion central recess 28 and an exterior wall 50 (FIG. 4) of the retainer hub portion 44 is a washer 52 having surfaces of a selected coefficient of friction. The retainer wall 50 is provided with a central opening 54. Disposed in the retainer hub portion 44 is a first end 56 of a brake coil spring 58, a second end 60 of the spring 58 having thereon a metal washer 62. A split pin 64 having a flared end 66 extends through the washer 62, the spring 58, and the retainer 42, and is press fitted into the center shaft 18. The coil spring 58 is compressed between the washer 62 and the retainer 42, urging the retainer wall 50 into firm engagement with the friction washer 52.
In operation, an operator pulls the rope 24, which extends through the housing 10. As the rope 24 is pulled outwardly, the pulley 20 is caused to rotate on the center shaft 18. The brake assembly 40, including the retainer 42, initially remains stationary because of the frictional engagement of the retainer 42, the friction washer 52, and the central shaft 18. The retainer hub portion 44 is pressed by the spring 58 into engagement with the stationary friction washer 52, and therefore resists turning. As the pulley hub portion 26 rotates, the moving pawls 36 engage the retainer protrusions 46, pivoting the pawls outwardly, causing the retainer 42 to rotate with the pulley hub portion 26. The free ends of the pawls extend well beyond the pulley hub portion 26 and the retainer 42 (FIG. 3). The resistance to turning of the retainer 42 is not so strong as to prevent turning, but merely places on the retainer 42 sufficient resistance so that the pawls 36 may firmly engage the retainer protrusions 46. Rotation of the hub portion 26 is transmitted by the pawls 36 to a coupling (not shown) that turns an engine crankshaft (not shown).
As may be seen in FIGS. 1-7, the prior art device over which the invention herein constitutes an improvement, includes a multi-component brake assembly which includes a central pin requiring press-fitting. It would be advantageous to reduce the number of parts of the brake assembly and to provide a brake assembly which can be connected to the remainder of the starter without the use of special tools.
Further, the metal pawls of the prior art device shown in FIGS. 1-7 often rattle against the metal retainer, raising a noise problem in the use of the starter.
Still further, in the prior art starter, to change the frictional load resisting rotation of the pulley, one may change the coefficient of friction of the friction washer and/or change the brake spring. Each affects the other and the changes must be accurately coordinated. In practice, changes usually are effected by simply packing the brake assembly with a special grease. It would be beneficial to be able to change the frictional load by a single change in the brake assembly and to not have to introduce special greases.